Table 7. Summary of results from multiple linear regression models.

Independent variable a)	VRT b)		DSB b)		VSRT b)		PAT b)
	Beta	p-value	Beta	p-value	Beta	p-value	Beta	p-value
Exposure status	−0.161	<0.001*	−0.018	0.727	−0.048	0.346	−0.186	<0.001*
Age	0.100	0.101	−0.045	0.504	0.268	<0.001*	0.146	0.011#
Years of education	0.349	<0.001*	0.236	<0.001*	0.077	0.245	0.406	<0.001*
Familiarity with computer games	0.179	<0.001*	0.063	0.201	0.057	0.240	0.24	<0.001*
Sex	−0.194	<0.001*	−0.007	0.886	−0.028	0.566	−1.05	0.012#
Length of residency	−0.002	0.973	−0.075	0.155	−0.020	0.716	−0.003	0.948
BMI	−0.053	0.251	0.035	0.485	0.071	0.151	0.005	0.913
Second-hand smoke	0.025	0.582	−0.031	0.523	−0.026	0.593	−0.021	0.618
Sleep status	0.014	0.751	0.110	0.016#	0.033	0.496	−0.020	0.636
Household fuel	0.034	0.457	0.023	0.644	0.021	0.666	−0.063	0.134
High-tension lines surrounding residence	−0.097	0.062	0.029	0.553	0.010	0.841	−0.068	0.105
Frequent use of household appliances	−0.016	0.719	−0.030	0.545	0.001	0.986	0.024	0.573

^a)Independent variables included exposure status(0 = school A, 1 = school B), age(years), years of education(years), familiarity with computer games (0 = little to none, 1 = much), sex(0 = male, 1 = female), length of residency(years), body mass index(BMI), second-hand smoking (0 = no,1 = yes), sleep status(0 = bad, 1 = not bad, 2 = good), household fuel (0 = coal, 1 = liquified petroleum gas, 2 = electricity, 3 = others), high-tension lines surrounding residence (0 = no,1 = yes) and frequent use of household appliances(0 = no,1 = yes).

^b)4 different multiple linear regression models were done considering NAI scores of VRT, DSB, VSRT and PAT as dependent variables. Backward selection for independent variable was used in the model with the entry significance level set to 0.05 and a removal level of 0.10.

^#Independent variable reserved in the model was with a p-value <0.05;

^*Independent variable reserved in the model was with a p-value <0.001.

Beta = standardized coefficients; VRT = visual retention test; DSB = digit symbol; VSRT = visual simple reaction time; PAT = pursuit aiming test.